Open Source or, in more common parlance, "complementary" currencies are collaboratively established units representing hours of labor that can be traded for goods or services in lieu of centralized currency...

It's what the Japanese did at the height of the recession. No, not the Japanese government, but unemployed Japanese people who couldn't afford to pay healthcare costs for their elder relatives in distant cities. They created a currency through which people could care for someone else's grandmother, and accrue credits for someone else to take care of theirs...

Turning currency into an collaborative phenomenon is the final frontier in the open source movement.